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GPS Rollover Week: What to Know

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GPS Rollover Week

What is GPS Rollover Week?

GPS provides a current date and time, represented as a week number. The week number parameter is generated via a 10-bit binary number. The valid range for the week number parameter is 0 to 1,023, for a total of 1,024 weeks. After that time, the week number rolls over to 0. 

The first week number period started when GPS was launched in January 1980, and the last GPS WNRO was 19.7 years ago, on Aug. 21, 1999. The next WNRO occurs on April 6, 2019, when the week number will again reach the maximum value of 1,023 and roll over to 0.

Any GNSS receiver that does not account for this rollover will report an erroneous date. This is an urgent required action and receivers will not function correctly without the correct firmware.

Preparing Your Spectra Geospatial GNSS Receiver

To prepare for the week number rollover event, it is recommended to install, at minimum, the version number corresponding to each receiver in the below table before the rollover event occurs on April 6, 2019. All receivers with the firmware listed will continue to operate normally following the rollover.

If a receiver does not have, at minimum, the version listed in the table below, the receiver will output incorrect GPS week number, UTC time, and incorrect date in the output messages, data files, and in the WebUI (if applicable). Availability and reliability of GNSS positioning will be significantly degraded in real-time mode as well as in post-processing.

Firmware by Receiver Type

Receiver Minimum firmware version and comments
SP90m  V3.68
SP80 V3.38 (for expired SP80 firmware maintenance – SP Loader V8.8)
SP60 V3.81
SP60 V3.38 (for expired SP60 firmware maintenance – SP Loader V8.8)
SP20 V3.67
MM50 Not impacted by GPS Week Number Rollover
ProMark 800 V1.9.S815Kn27
ProFlex 800 V2.06.S850Kn27
ProMark 700 V4.70 or later
ProMark 100/200 V2.5.aW215Hm27
ProMark 100/220 V2.5.aW215Hm27
MobileMapper 100/120 V2.5.aW215Hm27
MobileMapper 300 V4.91 or later
EPOCH 50 V4.00 or later
EPOCH 35 V3.62 or later
EPOCH 25 V2.32 or later
EPOCH 10 V1.00 or later
ProMark 500 V6.8.S814G126
ProFlex 500 V4.5.S767G224

Users who are using any of the receivers in this table must ensure that they have upgraded to the minimum firmware for each receiver prior to the rollover event on April 6/7 2019. This is an urgent required action and receivers will not function correctly without the correct firmware.

For SP60 and SP80 firmware V3.38, Spectra Precision Loader V8.8 or later is required.

For SP90m firmware V3.68, Spectra Precision Loader V7.1.0 or later is required.

For post-processing of raw data recorded after April 6, 2019 in Survey Office, Patch 3 is required to be downloaded in Survey Office (available from Software Updates in Survey Office).

The applicable GPS Week Number Rollover receiver firmware versions in the above table are backwards compatible with the current Survey Pro version.

Trimble Geospatial Support Bulletin | Spectra Geospatial Support Bulletin
Trimble Firmware Recommendations | Spectra Firmware Recommendations

For More Information, Please Contact Your Local PLI Sales & Support Rep.

Pittsburgh, PA 724-266-1600
Columbus, OH 614-759-1000
Cincinnati, OH 513-539-0022
Cleveland/Akron, OH 330-633-4900
Charleston, WV 504-776-1831
Bridgeport, WV 304-933-3036